Not applicable.
Not applicable.
This invention relates to ring binders, and more particularly, to improvements in a xe2x80x9ccrownxe2x80x9d or clinch fastener for securing the shield of a binder ring mechanism to a spine portion of a binder. The fastener is a concealed fastener which securely attaches the mechanism to the binder spine, but does not penetrate through a cover of the binder so the fastener""s presence is not visible and the ring binder has a desired cosmetic appearance. Use of the crown fastener further simplifies the manufacturing process used to make a binder by eliminating operations previously required with other concealed fasteners.
Over the last few years there have been a number of developments in concealed fasteners for use in attaching a binder ring mechanism to the cover portion of a binder. The attractiveness of the fasteners recently developed is that while they secure the mechanism to the binder, the fastener is not readily visible. In particular, unlike rivets previously used for attachment purposes, there is nothing showing on the outside of the binder. This results in a cleaner, more attractive appearance.
Up until the development of the clinch fastener disclosed in co-assigned U.S. Pat. No. 6,019,538 (the ""538 patent), concealed fastener development, including that done by the assignee of this application and the ""538 patent, has involved a fastener construction employing a base plate (typically rectangular, but also round) from which is struck a plurality of prongs. The prongs all extend from the same side of the base plate and are used to attach the fastener to a of compressed cardboard or similar backing which forms the binder spine. Extending from the opposite side of the base plate has been a post the outer end of which projects through an opening in the shield of the binder ring mechanism. The post not only acts as a spacer to space the binder ring mechanism from the binder spine, but the post is also secured to the shield, so to attach the fastener to the mechanism. In some prior art constructions the post is formed with base plate. In other constructions, for example, the Schuessler U.S. Pat. No. 5,160,209, the post is a separate piece. In some concealed fastener constructions, the fastener is used with a spacer or eyelet which fits over the post and facilitates attachment of the fastener to the mechanism. In addition to the U.S. Pat. No. 5,160,209 mentioned above, the following United States Patents show and describe various concealed fastener constructions or improvements to these constructions; Cooper et al. U.S. Pat. No. 5,035,526, Cooper U.S. Pat. No. 5,100,253, To U.S. Pat. Nos. 5,755,513, 5,772,348 and U.S. Pat. No. 5,842,807, Cheng U.S. Pat. No. 5,879,097, Whaley U.S. Pat. No. 5,903,958, To U.S. Pat. Nos. 5,924,811, 5,971,649, and 5,980,146, To et al. U.S. Pat. No. 5,924,811, Whaley U.S. Pat. No. 6,007,265, Cheng et al. U.S. Pat. No. 6,007,266, and Whaley design U.S. Pat. Nos. 414,802, 414,803, and 414,804.
With the exception of the ""538 patent, when fabricating a binder using the above-noted prior art concealed fastener constructions, a pair of concealed fasteners are first attached to respective ends of the shield. This is accomplished by inserting the outer end of the posts through openings formed in each end of the shield from the underside of the shield. The outer ends of the posts are then upset about the outer surface of the shield adjacent the respective openings. In some constructions, such as shown in the Schuessler ""209 patent, a separate sleeve or eyelet must be installed on the post so as to hold the shield in its desired relationship with the binder when the outer end of the post is upset. In other applications, as shown in To ""807 patent, the post has a narrower outer end which is inserted through the opening in the shield such that when the outer end of the post is upset, the shield is rigidly secured to the post between shoulder on the post and the upset head. In any event after prior art fasteners are secured, the prongs formed in, and extending from the fastener plate are pressed into the spine material. The force used to press them into the cardboard backing causes the prongs to splay outwardly so a thickness of cardboard is compressed between the fastener plate and the prongs.
The clinch fastener described in the ""538 patent departs from the previous designs in that this fastener has no base plate nor a post drawn from the base plate for attaching the fastener to the shield of the mechanism. Rather, this clinch fastener comprises a cylinder closed at one end and with prongs formed at the opposite, open end of the cylinder. The outer surface of the closed end of the cylinder is abutted against the underside of the shield and the clinch fastener is attached to the shield by striking the outer surface of the shield with a tool thus to interlock the end of the cylinder and the shield in a clinched relation. This action forces a portion of the shield into the surface formed by the closed end of the cylinder and at the same time deforms a portion of this surface about the shield. As with the prior art fasteners, two clinch fasteners are used, with a fastener being attached to each end of the shield. After the sub-assembly is formed, the prongs formed on the opposite end of the clinch fastener are pressed into the backing material to attach the sub-assembly to the binder spine.
Besides the clinch fastener described in the ""538 patent being a concealed fastener, the fastener has other advantages over the prior art fasteners. Testing has found that the clinch fastener has better holding strength than conventional concealed fasteners, particularly when subjected to side loads. This is important because if a fastener is unable to keep the binder ring mechanism from being torn away from the binder spine when the binder is in use, then the appearance aspect provided by the fastener is superfluous. The addition of spurs to the ends of the prongs on the clinch fastener, such as taught in co-assigned Whaley U.S. Pat. No. 5,903,958, helps increase the holding power of the fastener. Further in this regard, as described above, when the prongs of conventional concealed fasteners are driven into the cardboard backing board material of the binder spine, the cardboard is sandwiched between the fastener plate and the prongs. This compresses and fractures the cardboard, weakening it and making it easier to pull the fastener away from the binder spine.
In addition to improved holding strength, the clinch fastener simplifies manufacturing operations. This is because certain conventional concealed fasteners (such as shown in the ""709 and ""807 patents, but not the ""538 patent) require holes to be drilled into the shield so the fasteners""posts can be inserted through them. The clinch fastener does not require any such openings, thus saving a manufacturing step.
While the clinch fastener described in the ""538 patent has these various advantages, further improvements can be made. For example, in binder testing, it has been found that repeated side loads on the shield assembly (as when a user turns a large number of pages inserted in the binder) can cause the assembly to pull away from the binder spine even when relatively low levels of force are applied. The crown fastener of the present invention solves this problem in addition to providing increased holding capability over the clinch fastener described in the ""538 patent.
Among the several objects of the present invention may be noted the provision of a xe2x80x9ccrownxe2x80x9d or clinch fastener for attaching the ring mechanism of a binder to a spine portion of the binder. The clinch fastener is a concealed fastener that does not penetrate through to the outside of a binder cover when the fastener is attached to the binder spine. The fastener thus is not visible when in place and creates a desired cosmetic appearance for the binder.
A further object of the invention is an improved clinch fastener having two sets of prongs or teeth for attaching the fastener to the spine backing material. The first set of prongs splay outwardly relative to the longitudinal centerline of the fastener when the fastener is attached to the backing material and spurs are formed on the ends of the prongs to better grip the material. The second set of prongs are shorter in length than the first set, and alternate with the prongs comprising the first set. Each of the prongs of the second set are inwardly turned. These prongs also grip the spine backing material. Having two sets of prongs splayed in opposite directions improves the holding capability of the fastener, and prevents twisting of the binder ring mechanism relative to the binder when the binder is subjected to side loads. These features make the binder more durable and capable of withstanding a great amount of force without the shield portion of the assembly separating from the binder cover.
Another object of the invention is an improved clinch fastener in which the length of the prongs forming the second set generally correspond to the thickness of the backing material whereas the length of the prongs forming the first set is greater than the backing thickness. During attachment of the crown fastener to the backing material, the prongs forming the second set penetrate the backing material at a shallow angle whereas the prongs forming the first set splay outwardly at a somewhat greater angle. Regardless, neither set of prongs penetrate through the backing material so none of the prongs of either set are visible on the outside of the binder.
Yet another object of the invention is an improved clinch fastener in which a pair of fasteners are used, one at each end of the binder ring mechanism, to secure the mechanism to the binder. Importantly, because no portion of either fastener has to extend through the shield of the mechanism in order for the fasteners to be attached to the shield, the manufacturing process requires fewer steps. Since the fastener is attached to the underside of the cover and does not extend through any opening in the shield, the fastener is not visible when the binder is open either. Also, the fasteners can readily be used with automated equipment for the volume manufacture of ring binders.
Finally, it is an object of the invention to provide an improved clinch fastener which is a low cost fastener but provides a very strong means for attaching the binder ring mechanism to the binder and to do so while providing a desired cosmetic appearance.
In accordance with the invention, generally stated, a concealed clinch fastener, which is also referred to as a xe2x80x9ccrownxe2x80x9d fastener, includes a cylindrical body closed at one end. This closed end of the fastener forms a surface deformable to attach the fastener to the shield of a binder ring mechanism by abutting the surface against the underside of the shield and striking the shield with a tool to deform a portion of the shield and surface about each other. A first set of prongs are formed at an opposite, open end of the fastener body and project outwardly therefrom to attach the fastener to the binder when the prongs are driven into the backing to secure the fastener to the backing. A second set of prongs are also formed at the open end of the cylinder, but these prongs extend inwardly rather than outwardly. The prongs comprising the second set are shorter in length than those comprising the first set and are also driven into the backing material. The prongs forming the second set both increase the holding strength of the clinch fastener and prevent twisting of the binder ring mechanism once attached to the binder. Other objects and features will be in part apparent and in part pointed out hereinafter.